<?php	
//8.Select * from student where sid=1 group by sex having sex=’男’ order by sid desc limit 1

//11.select * from stu join class on stu.cid=class.cid

//18.select * from stu right join class on stu.cid=class.cid where sid=null;

//20.
//select * from tag as t join arc_tag as at on t.tid=at.tid;

select t.tname,count(*) from tag as t join arc_tag as at on t.tid=at.tid group by t.tname;





















